1. Field of the Invention
The present invention relates to a thin film transistor array substrate and a method of fabricating the same, and more particularly, to a thin film transistor array substrate and a method of fabricating the same, in which electrical characteristics of an oxide semiconductor layer are improved.
2. Description of the Related Art
A liquid crystal display (LCD) is one of most widely used flat panel display configurations. The LCD includes two substrates on which electrodes are formed, and a liquid crystal layer interposed between the two substrates. Voltages are applied to the electrodes to realign the liquid crystal molecules of the liquid crystal layer and control the amount of light that is transmitted through the liquid crystal layer.
Among the different types of LCDs, the most common structure involves positioning electric field-generating electrodes on each of first and second substrates. A plurality of pixel electrodes are arranged in a matrix configuration on the first substrate (i.e., thin film transistor array substrate), and a single common electrode is positioned covering the entire surface of the second substrate.
The display of images is achieved by applying a separate voltage to each of the pixel electrodes. To realize such operation, a three-terminal thin film transistor is connected to each pixel electrode in order to perform switching of the voltage applied thereto, and a plurality of wiring structures, which include gate lines for transmitting signals for controlling the thin film transistors and data lines for transmitting the voltages applied to the pixel electrodes, are formed on the substrates.
In the conventional LCD, amorphous silicon thin film transistors or polycrystalline silicon thin film transistors are used, depending on the material forming the channel regions of the switching elements. Amorphous silicon thin film transistors have a low charge mobility at approximately 0.5 cm2/Vs, but allow uniform electrical characteristics to be achieved in large display devices. Polycrystalline silicon thin film transistors, on the other hand, have a high charge mobility of approximately several hundred cm2/Vs, but make it difficult to achieve uniform electrical characteristics in a large display device.